Bacterial interaction is known for generating electricity, making a new type of batteries possible. There are two main mechanisms behind biobatteries – one that uses bacteria as a fuel source and one that use enzymes to generate power.
The problem is that such a battery produces electricity only for a short period, from minutes and hours to maybe days. But now Chinese researchers claim to have achieved unprecedented self-charging capabilities and high efficiency. The report is published in the journal Advanced Materials.
The team led by Zhong Chao, Liu Zhiyuan, and Wang Xinyu from the Shenzhen Institutes of Advanced Technology of the Chinese Academy of Sciences, collaborating with Wang Renheng from the Shenzhen University, developed a miniaturised, portable bio-battery that enables precise control over bioelectrical stimulation and physiological blood pressure signals. They used hydrogel technology to achieve the promising results.
In their laboratory the researchers encapsulated Shewanella oneidensis bacteria MR-1 biofilms within alginate hydrogels to develop living hydrogels, which can be 3D printed into defined geometries for customised fabrication. Inspired by lithium-ion batteries, they developed a miniaturised bio-battery (20mm in diameter, 3.2mm in height) using living hydrogel as the bio-anode ink, K3[Fe(CN)6]-containing alginate hydrogel as the cathode ink, and a Nafion membrane as the ion exchange membrane.
The metabolic activity of the bacteria generated electricity, enough to enable it with self-charging capabilities up to 10 cycles. Impressively, the bacteria in the bio-battery maintained a high viability of more than 70% across the entire process and 97.6% at the end of operation. The cell had a specific capacity of 0.4mAh g−1, a maximum power density of about 8.31µW cm−2, and an energy density of 0.008Wh/L. Although these values are lower than those of traditional lithium-ion batteries, the bio-battery provides a sustainable energy alternative.
Pic: Living hydrogels to prepare portable energy devices for neuron stimulation. Credit SIAT
